1. Field of the Invention
The present invention relates to a method for manufacturing a component incorporating module having a resin layer incorporating a circuit component and the component incorporating module.
2. Description of the Related Art
In response to the recent increase in capacity and miniaturization of electronic apparatuses, there are increased demands for further miniaturization and increased densification of electronic components provided in circuit boards. Under these circumstances, a component incorporating module which obtained a high density by incorporating a plurality of circuit components in a resin layer has been proposed.
Japanese Unexamined Patent Application Publication No. 11-220262 discloses two typical methods for manufacturing a component incorporating module which are associated with the formation of circuit patterns connected to circuit components to be incorporated in an insulation substrate.
FIG. 2 of Japanese Unexamined Patent Application Publication No. 11-220262 illustrates a method for providing circuit components on a plain copper foil which has not been patterned, hardening the circuit components using a resin, and forming circuit patterns by etching the copper foil from a rear side thereof.
Furthermore, FIG. 3 of Japanese Unexamined Patent Application Publication No. 11-220262 illustrates a method for forming circuit patterns on a mold release film, providing circuit components on the circuit patterns, hardening the circuit components using resin, and removing the mold release film.
In the former method, since the circuit components are connected to a plain copper foil, portions corresponding to lands (foot patterns) for mounting the components and portions corresponding to lines cannot be distinguished from one another in the copper foil. Therefore, when the circuit components are connected to the copper foil by soldering, the components may be moved from predetermined locations or solder may protrude to the portions corresponding to the lands adjacent to the solder.
In the latter method, since the components are provided on the patterns formed on the mold release film, the components are prevented from being moved and solder is prevented from protruding as compared to the former method. However, since lands for mounting the components and portions corresponding to wiring are continuously arranged, the components may be moved by the wiring used to connect components to one another during reflow processing. Furthermore, when the circuit components are connected to the circuit patterns using solder bumps, the solder may protrude to wiring portions located between terminals. Therefore, heights of the bumps may not be uniform after the reflow processing and stresses may be unevenly applied to the terminals.
To address these problems, a method for forming a solder resist film on a cooper foil or circuit patterns has been proposed. However, in this method, an additional resist film is required and the depth and the height of a module cannot be sufficiently reduced. In addition, the number of processing steps is increased, which results in an increase in cost. Furthermore, when the solder resist film is formed on a component mounting surface and a resin layer is formed on the solder resist film, since the component mounting surface is not sufficiently attached to the resin layer, a gap is likely to be produced between the resin layer and the resist film or between the resist film and an electrode. The gap may cause solder flashing, because the solder which is remelted and swollen in the module due to the high temperatures generated when the module is connected to a circuit board (mother board, for example) by soldering protrudes into the gap. Furthermore, since displacements of the wiring and the resist must be taken into consideration, a problem arises in that the board is not designed to conform to small intervals between the terminals of the components.
The problems described above arise when the circuit components are connected to a plain electrode or circuit patterns by soldering. However, even when a conductive adhesive agent or metal bumps are used for the connection instead of soldering, the conductive adhesive agent may unnecessarily protrude or the circuit components may be displaced relative to the predetermined locations. Therefore, the locations of the circuit components are not fixed, which results in a deterioration in reliability.